Brin Freund

Lance-Adams Syndrome in the Pretargeted Temperature Management Era: A Case Report and Systematic Review.

Acute posthypoxic myoclonus portends a poor prognosis. Another form of posthypoxic myoclonus, Lance-Adams syndrome, is associated with a better outcome. Differentiating these two entities is important in prognostication and guiding further medical intervention. This can be difficult in the acute setting after hypoxic brain injury but the use of neurophysiologic studies may be helpful. In this article, we present a case of a patient who presented after pulseless electrical activity arrest, underwent targeted temperature management and subsequently developed Lance-Adams syndrome. The neurologic and electroencephalographic findings in Lance-Adams syndrome are discussed with an updated review.

Myoclonus after cardiac arrest: Where do we go from here?

Prognostication after cardiac arrest often depends primarily on neurological function, and characterizing the extent of neurological injury hinges on neurophysiological testing and clinical neurological examination. The presence of early posthypoxic myoclonus (PHM) following cardiac arrest had been invariably associated with poor outcome, but more recent studies have shown that those with early PHM may survive with good neurological function. Electroencephalographic patterns suggestive of severe brain injury may be more valuable than the presence of PHM itself in portending poor functional status, and phenotyping PHM may also be useful in delineating benign and malignant forms. Patients with early PHM should be evaluated similarly to others who suffer cardiac arrest by using a multimodal approach in determining prognosis until further studies are performed that better characterize early PHM subtypes and their outcomes.

Post-hypoxic myoclonus: Differentiating benign and malignant etiologies in diagnosis and prognosis

Highlights • Myoclonus status epilepticus may be reflected by generalized epileptiform discharges and burst suppression on EEG.• Patients with Lance-Adams syndrome often demonstrate focal epileptiform activity at the vertex on EEG.• EEG is vital in evaluating post-hypoxic myoclonus; studies are needed to assess its utility in predicting outcomes.

Differentiating Lance–Adams syndrome from other forms of postanoxic myoclonus

In the recent article by Elmer and colleagues entitled “Clinically Distinct Electroencephalographic Phenotypes of Early Myoclonus after Cardiac Arrest,” the authors evaluated electroencephalographic differences in early postanoxic multifocal myoclonus (PAMM) and their use in diagnosis and prognosis. They described two distinct electroencephalographic (EEG) patterns predicting disparate outcomes: vertex spike–wave complexes, denoting Lance–Adams syndrome (LAS); and suppression–burst background with high-amplitude spikes, representing those previously described as “acute” PAMM, with abysmal survival. Their findings not only allow for differentiating these two conditions electroencephalographically, but taken a step further, allow for a necessary change in the way we discuss and interpret early PAMM. Previously, these two forms of PAMM were differentiated by the time of onset. However, in our recent review, 20% of cases of LAS were diagnosed within the first 48 hours. This is likely an underestimate given that, as Elmer and colleagues astutely point out, sedation can mask signs of awakening, and particularly because LAS is more easily differentiated from other forms of PAMM, with return of consciousness and stimulus-induced myoclonus. Therefore, the definition of each form should not be based on timing of myoclonus onset, as this may lead to misdiagnosis and inappropriate withdrawal of care. The findings of Elmer and colleagues emphasize that the distinction may be defined electroencephalographically, before awakening, as soon as 6 to 8 hours after return of spontaneous circulation. This could enable earlier diagnosis and guidance of intensive care and hypothermia protocols. We feel that EEG should be considered as part of the diagnostic criteria for LAS, given that these epileptiform discharges may persist with clinical myoclonus. This article presents novel findings that warrant further validation with longitudinal study, but should not lead practitioners to abandon clinical indicators for prognosis.

Neuromyelitis optica unmasked by a spinal dural arteriovenous fistula

Neuromyelitis optica spectrum disorder (NMO-SD) and spinal dural arteriovenous fistula (SDAVF) can both cause longitudinally extensive myelopathy. We describe a case of longitudinally extensive myelopathy attributed to a SDAVF. Despite treatment, myelopathy recurred and led to subsequent NMO-SD diagnosis. We consider a possible link between the two disorders which may shed light on the pathophysiology of NMO-SD. To our knowledge, this is the first published case of co-existent NMO-SD and SDAVF leading to myelopathy.

A Case of Morvan Syndrome Mimicking Amyotrophic Lateral Sclerosis With Frontotemporal Dementia.

Introduction: Morvan syndrome is a rare autoimmune/paraneoplastic disorder involving antibodies to the voltage-gated potassium channel complex. It is defined by subacute encephalopathy, neuromuscular hyperexcitability, dysautonomia, and sleep disturbance. It may present a diagnostic dilemma when trying to differentiate from amyotrophic lateral sclerosis with frontotemporal dementia. Methods: A 76-year-old man with a history of untreated prostate adenocarcinoma was evaluated for subacute cognitive decline, diffuse muscle cramps, and hyponatremia. Results: MRI demonstrated atrophy most prominent in the frontal and temporal regions. Electromyography (EMG) demonstrated diffuse myokymia/neuromyotonia. Polysomnography lacked REM and N3 sleep. Paraneoplastic panel detected antibodies to voltage-gated potassium channel complex (CASPR2 subtype). Conclusions: It is difficult to differentiate between Morvan syndrome and amyotrophic lateral sclerosis with frontotemporal dementia with examination and neuroimaging alone. There may be a link between Morvan syndrome and prostate adenocarcinoma which could help with screening/diagnosis. The authors found that laboratory and neurophysiological tests are indispensable in diagnosing and treating Morvan syndrome.

Seizure incidence in the acute postneurosurgical period diagnosed using continuous electroencephalography

OBJECTIVEDelay in diagnosis and subsequent treatment of nonconvulsive seizures can lead to worsened outcomes. The gold standard in detecting nonconvulsive seizures is continuous video-electroencephalography (cEEG). Compared to routine, 30-minute EEG, the use of cEEG increases the likelihood of capturing intermittent nonconvulsive seizures. Studies of critically ill patients in intensive care units demonstrate a particularly high rate of nonconvulsive seizures. Some of these studies included postneurosurgical patients, but often subanalyses of specific populations were not done. In particular, few studies have specifically evaluated postneurosurgical patients by using cEEG in the acute postoperative setting. Therefore, the incidence and predictors of acute postneurosurgical seizures are unclear.METHODSIn this study, the authors focused on patients who were admitted to the neurological critical care unit following neurosurgery and who underwent cEEG monitoring within 72 hours of surgery.RESULTSA total of 105 cEEG studies were performed in 102 patients. Twenty-nine patients demonstrated electrographic (subclinical) seizures, of whom 10 had clinical seizures clearly documented either before or during cEEG monitoring. Twenty-two patients had subclinical seizures only detected on cEEG, 19 of whom did not have clinical seizure activity at any point during hospitalization. Those with seizures were more likely to have had a history of epilepsy (p = 0.006). The EEG studies of patients with seizures were more likely to show lateralized periodic discharges (p = 0.012) and lateralized rhythmic delta activity (p = 0.012). The underlying neuropathological disorders most associated with seizure risk were lobar tumor on presentation (p = 0.048), subdural hematoma (SDH) requiring craniotomy for evacuation (p = 0.002), subarachnoid hemorrhage (SAH) (p = 0.026), and perioperative SAH (p = 0.019). In those undergoing craniotomy, the presence of SDH (p = 0.032), particularly if requiring evacuation (p = 0.003), increased the risk of seizures. In those without preoperative intracranial bleeding, perioperative SAH after craniotomy was associated with a higher incidence of seizures (p = 0.014). There was an additive effect on seizure incidence when perioperative SAH as well as concomitant intraparenchymal hemorrhage and/or stroke were present. The clinical examination of the patient, including the presence or absence of altered mental status and the presence or absence of repetitive movements, was not predictive of subclinical seizures.CONCLUSIONSIn postneurosurgical patients referred for cEEG monitoring, there is a high rate of both clinical and subclinical seizures in the early postoperative period. Seizures are particularly common in patients with SDH or lobar tumor and perioperative SAH. There was an additive effect on seizure incidence when more extensive brain injury was present. As expected, those with a history of epilepsy also demonstrated higher seizure rates. Further studies are needed to evaluate the time period of maximum seizure incidence after surgery, and the effects acute postneurosurgical seizures have on long-term outcomes.

EEG Differences in Two Clinically Similar Rapid Dementias: Voltage-Gated Potassium Channel Complex–Associated Autoimmune Encephalitis and Creutzfeldt-Jakob Disease

Distinguishing treatable causes for rapidly progressive dementia from those that are incurable is vital. Creutzfeldt-Jakob disease (CJD) and voltage-gated potassium channel complex–associated autoimmune encephalitis (VGKC AE) are 2 such conditions with disparate outcomes and response to treatment. To determine the differences in electroencephalography between CJD and VGKC AE, we performed a retrospective review of medical records and examined clinical data, neuroimaging, and electroencephalographs performed in patients admitted for evaluation for rapidly progressive dementia diagnosed with CJD and VGKC AE at the Johns Hopkins Hospital and Bayview Medical Center between January 1, 2007 and December 31, 2015. More patients in the VGKC AE group had seizures (12/17) than those with CJD (3/14; P = .008). Serum sodium levels were lower in those with VGKC AE (P = .001). Cerebrospinal fluid (CSF) white blood cell count was higher in VGKC AE (P = .008). CSF protein 14-3-3 (P = .018) was more commonly detected in CJD, and tau levels were higher in those with CJD (P < .006). On neuroimaging, diffusion restriction in the cortex (P = .001), caudate (P < .001), and putamen (P = .001) was more frequent in CJD. Periodic sharp wave complexes (P = .001) and generalized suppressed activity (P = .008) were more common on initial EEG in CJD. On serial EEGs, generalized periodic discharges (P = .004), generalized suppressed activity (P=0.008), and periodic sharp wave complexes (P < .001) were detected more in CJD. This study shows that there are a number of differentiating features between CJD and VGKC AE, and electroencephalography can aid in their diagnoses. Performing serial EEGs better delineates these conditions.